Sitting on the lap of his mother, Cindy Martinez, 9-year-old Darrell Taylor grimaces as he receives a flu vaccination during a free flu vaccine clinic Jan. 28, 2013, at the Capitol in Sacramento, Calif. / Rich Pedroncelli, AP

by Elizabeth Weise, USA TODAY

by Elizabeth Weise, USA TODAY

Although the flu is beginning to wane nationally, it is sickening and killing seniors at rates "higher than we've ever seen," a CDC flu expert says.

Last week, people older than 65 who died from a laboratory-confirmed case of influenza died at a rate of 116 per 100,000.

"We've kept rates since 2005 and we have never seen a rate this high," said Michael Jhung, an epidemiologist at the Centers for Disease Control and Prevention. "The highest we've ever seen in was 90 per 100,000."

He expects those numbers to go higher still. Hospitalization - and, in some cases, death - follows several weeks after a person first gets sick.

"We've still got several weeks of the season yet, so it's going to be much worse" before it's over, he said. "The deaths are still accumulating."

Each year, between 3,000 and 49,000 Americans die from influenza-related causes, the CDC estimates. So far this season, 45 children have died as a result of the flu. Numbers for adults won't be available until the flu season ends. The virus is surging in the West but is waning nationally:

9.4% of deaths reported in CDC's 122 Cities Mortality Reporting System were due to pneumonia and influenza as of Jan. 26. That's well above the epidemic threshold of 7.2% but down from 9.8% a week earlier.

The proportion of people visiting the doctor for influenza-like illness was 4.2% of all doctor visits, down from 4.3%the week before, CDC's FluView report showed. On average, the number is usually 2.2%.

Influenza is always more dangerous to people 65 and older, but it is worse this year because the prevalent flu strain - H3N2 - is especially dangerous to older people. "We haven't seen H3 viruses predominate like they are this year since the 2004-2005 season," Jhung said. Because of that, people have little immunity unless they were vaccinated this year.

"It has come out from under a rock and it's now dominant because there is a larger population of susceptible people," said William Schaffner, a professor of preventive medicine at Vanderbilt University in Nashville.

It's not too late to get vaccinated, Jhung said.

Someone who begins to feel sick should contact a doctor quickly. Antiviral drugs, taken within 48 hours of the onset of the flu, are helpful in preventing complications and keeping people out of the hospital, he said.

This year's flu season got off to an early start, hitting the East Coast especially hard in late December and early January. Several cities, including Boston and New York, declared flu emergencies.

"The wave this year went from the entire eastern part of the country and then moved west," Jhung said. Despite the downward tick, the flu continues to hit hard, especially in the West.

California, Oregon and Washington are still showing increases, Jhung said. While nationally 4.2% of visits to doctors offices are for flulike illnesses, in that part of the country the figure is 5.9%, up from 4.6% the week before.

Flu rates are at the highest levels seen in the past four years in Los Angeles, according to the Los Angeles County Public Health Department. In Los Angeles, seven adults have died of flu, six of them older than 65. All had H3N2, the Public Health Department reported Thursday.

In San Diego, 19 people had died as of Tuesday, the majority of whom had underlying illnesses, according to the city's Health and Human Services Agency.

In Oregon, rates of flulike illnesses are high, though so far this season no children have died from flu.